CN103795654A - Non-blocking Clos switching network design method based on AWG - Google Patents

Abstract

The invention discloses a non-blocking Clos switching network design method based on an AWG. The method aims to achieve the expandability and high utilization ratio of a large-scale optical switching network constructed based on the AWG. According to the method, a recursive switching network structure is established based on the recursive construction principle of the AWG and the wavelength isolation principle of a TWC, and therefore recursive decomposition of the whole switching network in the spatial dimension and wavelength dimension can be triggered; modularization of the AWG, reduction of the conversion range of the TWC and reuse of small wavelength sets in the switching network are effectively achieved under the condition that the utilization ratio of each device reaches 100%, and construction of the large-scale WDM switching network is made possible.

Description

Based on the clog-free Clos switching network method for designing of array waveguide grating

Technical field

The present invention relates to optical switching network technical field, particularly relate to a kind of clog-free Clos switching network method for designing based on array waveguide grating (AWG).

Background technology

Along with the exponential growth of communication network capacity demand, wavelength division multiplexing (WavelengthDivideMultiplex, WDM) optical-fiber network is owing to providing huge transmission bandwidth and good communication quality to develop rapidly.And in WDM optical-fiber network, AWG and tunable wavelength converter (TWC) combination is considered to build the up-and-coming alternative of WDM optical switch.

But at present the WDM optical switch based on AWG still faces problems, and wherein topmost be exactly scalability problem, its concrete reason be mainly following some:

(1), in the time that being input to of same wavelength is greater than 15 ports, the signal in AWG can suffer serious coherent crosstalk.This problem is difficult to solve by physical design.

(2) in actual applications, the price of TWC can be along with the increase of its conversion range significantly increases, and this makes to utilize the TWC of large conversion range to build extensive WDM switch and becomes uneconomical.

(3) the wavelength collection of each WDM optical switch can not be excessive, because in actual optical communication network, frequency spectrum resource is most valuable.

In order to overcome the problems referred to above, the WDM optical switch design based on AWG mainly contains following several at present:

The first scheme is configured respectively a TWC and is constructed the optical cross-matrix (crossbar) of the W × W based on AWG by the each input port of the AWG at a W × W.In this scheme, the dimension of AWG and the conversion range of TWC are W, and therefore autgmentability is very poor.On the other hand, AWG, by its wavelength channel, can provide W between its input/output port simultaneously ²bar connects.And in light crossbar, even if all input/output ports all at full capacity time, the linking number using is only W, therefore the utilance of AWG only has 1/W.

First scheme adopts to be forbidden exceeding 15 input ports and use simultaneously the swap status of same wavelength.Although this method has suppressed coherent crosstalk problem, it not only brings extra computation complexity, and has limited the use of some swap status of AWG, has reduced the utilance of AWG.

The third scheme is by only realizing zero coherent crosstalk with the part input port of AWG.Although this method can realize zero coherent crosstalk, it is equally to reduce AWG utilance as cost.On the other hand, the needed TWC conversion range of this method is greater than the actual input port number using, and this has just increased the extra cost of switch.

The 4th kind of scheme avoids using at many input ports the situation of same wavelength by the wavelength resource in the multiple free spectrum space of employing (FSR).The shortcoming of this method is following 2 points.On the one hand, AWG physical property in spectral range outside main FSR is very poor, and this can reduce the physical property of switch.On the other hand, the required TWC conversion range of switching network is several times as much as port number, and therefore to realize cost very high for this scheme.

The 5th kind of scheme is the multistage switching network adopting based on AWG, adopt many cross bar switches based on AWG this Structure Decreasing the requirement of conversion range of port number to AWG and TWC, can build large-scale switching network with the TWC of the AWG of less port and less conversion range.But this switching fabric is still take light crossbar as construction unit, and therefore in network, the utilance of AWG is still very low, and its internal level and level between physical connection complexity still very high, be O (N).

Therefore,, based on above reason, need to, for the extensibility of optical switching network and the utilance problem of network that build extensive AWG, provide a kind of clog-free Clos switching network method for designing based on array waveguide grating at present.

Summary of the invention

The object of the invention is for the extensibility of optical switching network and the utilance problem of network that build extensive AWG, a kind of clog-free Clos switching network method for designing based on AWG is provided, improves the extensibility of switching network, 100% utilance of acquisition internal components.

For achieving the above object, the clog-free Clos switching network method for designing that the present invention is based on array waveguide grating adopts following technical scheme:

A kind of clog-free Clos switching network method for designing based on AWG,: use array waveguide grating (AWG) and tunable wavelength converter (TWC) to build clog-free Clos switching network, decompose by recurrence modularization, the reduction of TWC wavelength conversion scope, the wavelength collection of realizing AWG and reuse in network, thereby realized the extensibility of WDM optical switching network and 100% utilance;

Comprise following parameter:

N: the exchange scope of large-scale switch allows at most to participate in the wavelength number of exchange simultaneously;

N: be the size of small-sized AWG;

d=log _nN，

And it is characterized in that:

The AWG of the AWG:n of n × n input, a n output;

The TWC module of n × n: the wavelength multiplexer by 1 × n wavelength demultiplexer, a n TWC and n × 1 forms;

N ^d× n ^dwDM switching network: this network packet is containing n ^d-1individual input port, n ^d-1individual output port, comprises d wavelength on each port, its function is that certain input wavelength of certain input port is exchanged in certain output wavelength of certain output port; Secondary AWG network N _in ^d-1, n: by n ^d-2the AWG of an individual n × n and n n ^d-2× 1 the interconnected formation of wavelength multiplexer; Secondary AWG network N ₀n,n ^d-1: by n n ^d-2× 1 AWG and n ^d-2the interconnected formation of wavelength demultiplexer of individual n × n; Three-level network δ _an,n ^d-1, n: by n ^d-1the TWC module composition input stage of individual n × n, n n ^d-1× n ^d-1tWC module composition intergrade, n ^d-1the TWC module composition output stage of individual n × n, between input stage and intergrade by a n ^d-1the AWG of × n is connected, between intergrade and output stage by n × n ^d-1aWG connect;

Three-level network δ _bn,n ^d-1, n: by n ^d-1the TWC module composition input stage of individual n × n, n n ^d-1× n ^d-1tWC module composition intergrade, n ^d-1the TWC module composition output stage of individual n × n, between input stage and intergrade by a N _in ^d-1, n network be connected, and between intergrade and output stage by N ₀n,n ^d-1network connects;

Three-level network δ _cn,n ^d-1, n: by n ^d-1the TWC module composition input stage of individual n × n, n n ^d-1× n ^d-1wDM switched sub-networks form intergrade, n ^d-1the TWC module composition output stage of individual n × n, between adjacent two-stage by n ^d-2the AWG of individual n × n connects;

Comprise the steps:

(1) for network δ _an,n ^d-1, n, first by n ^d-1the AWG of × n is decomposed into a secondary AWG network N _in ^d-1, n, as shown in Figure 2.Network N _iinput port α be marked as A, α, wherein α=0,1 ..., n ^d-1-1, A=α/n, α=[α] _n, α the input port of the AWG of A n × n of expression.At N _in ^d-1, in n, the wavelength collection relevant to the AWG of A n × n is

${\mathrm{\Λ}}_A=\{{\mathrm{\λ}}_{\mathrm{An}},...,{\mathrm{\λ}}_{(A+1)n-1}\}\⊆\mathrm{\Λ},$

And input port A, α and its γ output port pass through wavelength X _x∈ Λ _abe connected, wherein

x=An+[α+γ] _n

=α/nn+[[α] _n+γ _n。

Correspondingly by n × n ^d-1aWG be decomposed into a secondary AWG network N ₀n,n ^d-1.Above-mentioned decomposable process is by δ _a(n, n ^d-1, n is for conversion into δ _bn,n ^d-1, n, as shown in Figure 3;

(2) network δ _bn,n ^d-1, in n, each by a pair of n ^d-2× 1 wavelength multiplexer and a n ^d-1× n ^d-1the part of TWC module composition replace to a n ^d-1× n ^d-1wDM switching network, allow the AWG of all n × n be operated in Same Wavelength set Λ ₀=λ ₀..., λ _n-1upper, obtain three-level network δ _cn,n ^d-1, n, as shown in Figure 4.

(3) with a δ _cn,n ^d-2, n replaces δ _cn,n ^d-1, the each n in n ^d-1× n ^d-1wDM switching network, and then with a δ _c(n, n ^d-3, n replaces δ _c(n, n ^d-2, the each n in n ^d-2× n ^d-2wDM switching network, so recurrence repeats, until δ _cn,n ², the each WDM network in n is replaced by δ _cn, n, till n, finally realizes a n who is made up of the TWC module of n × n and the AWG of n × n ^d× n ^dthe WDM switching network based on AWG, and the wavelength collection of the required use of network is reduced to Λ ₀=λ ₀..., λ _n-1.

Compared with prior art, the invention has the beneficial effects as follows:

(1) by AWG modularization, reduce the required conversion range of TWC in network, reduce physical cross talk and the constructions cost of extensive AWG switching network;

(2) modular process of AWG has defined the horizontal line of demarcation of network, and TWC module wavelength conversion function has defined longitudinal line of demarcation.The little lattice of network of these line of demarcation definition have wavelength independence, reusable identical wavelength collection Λ ₀=λ ₀..., λ _n-1, saved the wavelength resource of communication window;

(3) when all input and output wavelength channels are all at full capacity time, can realize network 100% utilance.

Accompanying drawing explanation

Fig. 1 is three-level network δ _an,n ^d-1,n schematic diagram;

Fig. 2 is by the AWG of n × n and n ^d-2the two-level network N of × 1 multiplexer composition _in ^d-2, n schematic diagram;

Fig. 3 is three-level network δ _bn,n ^d-1, n schematic diagram;

Fig. 4 is three-level network δ _cn,n ^d-1, n schematic diagram;

Fig. 5 is a three-level network δ based on AWG _a2,8,2;

Fig. 6 is 8 × 2 AWG decomposing schematic representation;

Fig. 7 is and δ _a2,8,2 three-level network δ of equal value _b2,8,2;

Fig. 8 is δ _c2,8,2 subnet division network schematic diagrames;

Fig. 9 is the network δ after recurrence is decomposed _c2,8,2;

The former δ of Figure 10 _anetwork diagram after 2,8,2 network equivalents decompose.

Embodiment

Below in conjunction with the drawings and specific embodiments, further illustrate the present invention, should understand these embodiment is only not used in and limits the scope of the invention for the present invention is described, after reading the present invention, those skilled in the art all fall within the application's claims limited range to the modification of the various equivalent form of values of the present invention.

Based on a clog-free Clos switching network method for designing for array waveguide grating, be applied to specific embodiment, for three grades of switching network δ based on AWG as shown in Figure 5 _a2,2 ^4-1, 2, design equivalent Clos switching network and comprise the steps:

(1) first 8 × 2 AWG is decomposed into the two-level network N being formed by the AWG of 42 × 2 and two s' 4 × 1 multiplexer _i4,2.Wavelength collection Λ=λ that like this, originally 8 × 2 AWG is corresponding ₀, λ ₁..., λ ₇just be broken down into four subset Λ ₀=λ ₀, λ ₁, Λ ₁=λ ₂, λ ₃, Λ ₂=λ ₄, λ ₅and Λ ₃=λ ₆, λ ₇, they are the AWG of corresponding four 2 × 2 successively, as shown in Figure 6.

Similarly, according to the method described in (1), 2 × 8 AWG is also decomposed into equivalent two-level network N ₀2,4. Network δ _a2,2 ⁴¹, two AWG in 2 are by corresponding N _i4,2 and N _?2,4 substitute, just obtain three- level network δ _b2,8,2, as shown in Figure 7.

(2) network δ _b2, in 8,2, the part that each wavelength multiplexer by one 4 × 1, the TWC module of 8 × 8 and one 1 × 4 wavelength demultiplexer form replaces to the WDM commutator network of 8 × 8, all 2 × 2 AWG is relevant to Same Wavelength set, obtains three- level network δ _c2,8,2, as shown in Figure 8.

(3) with a δ _c2,4,2 replace δ _cthe WDM commutator network of each 8 × 8 in 2,8,2, as shown in Figure 7.And then with a δ _c2,2,2 replace δ _cthe WDM commutator network of each 4 × 4 in 2,4,2,16 × 16 the WDM switching network based on AWG of finally realizing that an AWG by 2 × 2 TWC module and 2 × 2 forms, and the wavelength collection of the required use of network is reduced to Λ ₀=λ ₀, λ ₁, as shown in figure 10.

The present embodiment is by AWG modularization, use 2 × 2 AWG of less port and the structure WDM optical switching network based on AWG on a large scale of 2 × 2 TWC, reduce the required conversion range of TWC in network, reduced physical cross talk and the constructions cost of extensive AWG switching network.Meanwhile, the modular process of AWG has defined the horizontal line of demarcation of network, and TWC module wavelength conversion function has defined longitudinal line of demarcation.The little lattice of network of these line of demarcation definition have wavelength independence, reusable identical wavelength collection Λ ₀=λ ₀, λ ₂.Thereby the required wavelength set of whole network is from δ _a2,2 ^4-1, Λ=λ that 2 networks are associated ₀, λ ₁..., λ ₇drop to Λ ₀=λ ₀, λ ₂.In addition, when all input and output wavelength channels are all at full capacity time, network can be realized 100% utilance.

Claims (3)

1. the clog-free Clos switching network method for designing based on array waveguide grating, comprises following parameter:

N: the exchange scope of large-scale switch allows at most to participate in the wavelength number of exchange simultaneously;

N: be the size of small-sized AWG;

d=log _nN，

It is characterized in that:

The AWG of the AWG:n of n × n input, a n output;

The TWC module of n × n: the wavelength multiplexer by 1 × n wavelength demultiplexer, a n TWC and n × 1 forms;

N ^d× n ^dwDM switching network: this network packet is containing n ^d-1individual input port, n ^d-1individual output port, comprises d wavelength on each port;

Secondary AWG network N _in ^d-1, n: by n ^d-2the AWG of an individual n × n and n n ^d-2× 1 the interconnected formation of wavelength multiplexer; Secondary AWG network N ₀n,n ^d-1: by n n ^d-2× 1 AWG and n ^d-2the interconnected formation of wavelength demultiplexer of individual n × n; Three-level network δ _an,n ^d-1, n: by n ^d-1the TWC module composition input stage of individual n × n, n n ^d-1× n ^d-1tWC module composition intergrade, n ^d-1the TWC module composition output stage of individual n × n, between input stage and intergrade by a n ^d-1the AWG of × n is connected, between intergrade and output stage by n × n ^d-1aWG connect;

Three-level network δ _bn,n ^d-1, n: by n ^d-1the TWC module composition input stage of individual n × n, n n ^d-1× n ^d-1tWC module composition intergrade, n ^d-1the TWC module composition output stage of individual n × n, between input stage and intergrade by a N _in ^d-1, n network be connected, between intergrade and output stage by N ₀n,n ^d-1network connects;

Three-level network δ _cn,n ^d-1, n: by n ^d-1the TWC module composition input stage of individual n × n, n n ^d-1× n ^d-1wDM switched sub-networks form intergrade, n ^d-1the TWC module composition output stage of individual n × n, between adjacent two-stage by n ^d-2the AWG of individual n × n connects;

The method specifically comprises the steps:

Step 1, by three-level network δ _an,n ^d-1, n is for conversion into three-level network δ _bn,n ^d-1, n:

By network δ _an,n ^d-1, n in n ^d-1the AWG of × n is decomposed into a secondary AWG network N _in ^d-1, n, by n × n ^d-1aWG be decomposed into a secondary AWG network N ₀n,n ^d-1;

Step 2, three-level network δ _bn,n ^d-1, n is transformed into three-level network δ _cn,n ^d-1, n:

By network δ _bn,n ^d-1, each by a n in n ^d-2× 1 wavelength multiplexer, a n ^d-1× n ^d-1tWC module and a 1 × n ^d-2wavelength demultiplexer form part replace to a n ^d-1× n ^d-1wDM switching network, make the AWG of all n × n be operated in Same Wavelength set Λ ₀=λ ₀..., λ _n-1on;

Step 3, will be with a δ _cn,n ^d-2, n replaces δ _cn,n ^d-1, the each n in n ^d-1× n ^d-1wDM switching network, and then with a δ Cn, n ^d-3, n replaces δ _cn,n ^d-2, the each n in n ^d-2× n ^d-2wDM switching network, so recurrence repeats, until+ _cn,n ², the each WDM network in n is replaced by δ _cn, n, till n.

2. a kind of clog-free Clos switching network method for designing based on AWG as claimed in claim 1, is characterized in that: by δ _an,n ^d-1, the n in n ^d-1the AWG of × n is decomposed into N _in ^d-1, n two-stage AWG network, and carry out on this basis recurrence decomposition, until switching network is decomposed into the network being formed by the TWC module of n × n and the AWG of n × n.

3. a kind of clog-free Clos switching network method for designing based on AWG as claimed in claim 1, is characterized in that: described by network δ _an,n ^d-1, n in n ^d-1the AWG of × n is decomposed into a secondary AWG network N _in ^d-1, n, specifically comprises: by network N _iinput port α be labeled as A, a, wherein α=0,1 ..., n ^d-1-1, A=α/n, a=α _n, a the input port of the AWG of A n × n of expression; At N _in ^d-1, in n, the wavelength collection relevant to the AWG of A n × n is

${\mathrm{\Λ}}_A=\{{\mathrm{\λ}}_{\mathrm{An}},...,{\mathrm{\λ}}_{(A+1)n-1}\}\⊆\mathrm{\Λ},$

And input port A, a and its output port pass through wavelength X _x∈ Λ _abe connected, wherein

x=An+[α+γ] _n

=α/nn+[[α] _n+γ] _n。

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